Extend custom executor with configuration injects

What does this MR do?

Extends Custom executor (being implemented with !1385 (merged)) with a configuration injection mechanism.

Why was this MR needed?

Please read #4346 (closed) for details

Are there points in the code the reviewer needs to double check?

⚠ Built on top of !1385 (merged), so it requires it to be merged first! ⚠

⚠ AFTER MERGING !1385 (merged), remember about changing the target branch here to master! ⚠

Does this MR meet the acceptance criteria?

• Documentation created/updated
• Added tests for this feature/bug
• In case of conflicts with master - branch was rebased

What are the relevant issue numbers?

Closes #4346 (closed)